1. comparison of coronal bacterial leakage between immediate versus delayed post-space preparation in root canals filled with resilon/epiphany W. W. Lyons, G. R. Hartwell, J. T. Stewart, B. Reavley, C. Appelstein & S. Lafkowitz Department of Endodontics, New Jersey Dental School, University of Medicine and Dentistry of New Jersey, Newark, NJ, USA AMITHBABU.C.B MSD-ENDODONTICS

3. INTRODUCTION The timing of the postspace preparation in canals filled with gutta-percha continues to be debated. Several articles claim that delayed post-space preparation in root canals filled with gutta-percha results in more apical leakage when compared to immediate post-space preparation

4. INTRODUCTION Resilon is a thermoplastic synthetic polymer-based root filling material. It has handling properties similar to guttapercha and may be softened with heat. Epiphany sealer with a Resilon core, hereafter referred to as Resilon/ Epiphany, did not demonstrate superior sealing properties when compared to gutta-percha used with AH Plus sealer.

5. AIM OF THE STUDY The purpose of this study was to compare the ability of Resilon/Epiphany to maintain an apical seal after immediate versus delayed post-space preparation using an ex vivo bacterial leakage model The null hypothesis is that immediate or delayed post-space preparation willnot affect the seal provided by the Resilon/EpiphanyTM material remaining in the apical portion of the root canal system.

6. NULL HYPOTHESIS the null hypothesis (H0) formally describes some aspect of the statistical behaviour of a set of data. This description is treated as valid unless the actual behaviour of the data contradicts this assumption. Thus, the null hypothesis is contrasted against another hypothesis

7. MATERIALS AND METHODS SAMPLE PREPARATION 8 maxillary anterior teeth with straight root with out any crack. Teeth were decoronated at 16mm. Patency established with 10 k file. Working length was determined with 10k file 0.5mm short of apex. Instrumented to a final apical size of 50..06 taper using rotary instrument.

8. MATERIALS AND METHODS Working length is established Irrigated with 3% sodium hypochlorite Canals were cleaned with 17% EDTA

9. METHOD The prepared roots were divided into 4 groups. In groups 1 &2 a size- 50, .06 taper Resilon master cone was fitted into the canal with tug-back to within 0.5 mm of the working length. The canal was prepared and Resilon master cone, coated with Epiphany sealer, was seated into the root canal

10. METHOD A System B (SybronEndo,Orange, CA, USA) heat source at 150 C and a power setting of 10 was used to downpack the Resilon and anObturaII (Obtura Spartan, Fenton, MO, USA) unit with thermoplasticizedResilon was used to backfill the canal. The Obtura II was set to 160 C per manufacturer’s instructions and the thermoplasticizedResilon was delivered into the root canal through a 23-gauge

11. METHOD For group 1, the post-space was created immediately after canal filling. A System B unit with a .06 tapered tip was used to remove the coronal 6 mm and Gates Glidden drills (Roydent, Johnson City, TN, USA) at 9000 rpm were used to remove the remaining Resilon/ Epiphany to a depth that left 4 mm of the material in the apical portion of the root canal (Solano et al. 2005).

12. METHOD For group 2, the teeth were placed in 100% humidity at 37 C for 5 days to assure final set of the sealer. At the end of the 5 days, the post-space was created as described for group 1. For group 3 (positive control) the 20 root canals were filled with a size-50, .06 taper Resilonmaster cone fitted to tug-back, but with no Epiphany sealer

13. METHOD The 20 teeth in group 4 (negative control) were instrumented and no filler material was placed. The teeth were completely sealed with fingernail polish (Pink Diamond Shine, Sally Hansen, Uniondale, NY, USA).

14. BACTERIAL LEAKAGE MODEL Two coats of fingernail polish were applied to each root, leaving the apical 2 mm and coronal canal orifice clear. A hole was created in the screw cap of a 20 mL scintillation vial (Sigma-Aldrich Co., St. Louis, MO, USA). Each root was then placed through the hole in the cap so that the root end extended about 14 mm into the glass via

15. BACTERIAL LEAKAGE MODEL The caps with the attached roots were then screwed onto the vials. Each apparatus was then autoclaved using standard steam sterilization. After autoclaving the glass vials were filled with Brain Heart Infusion broth (Sigma-Aldrich Co.). The caps, with the roots fixed in place, were seated into the glass vials so that the root end was completely immersed in the broth. ten microlitres of streptococus mutants were introduced into post space.

16. BACTERIAL LEAKAGE MODEL Bacterial leakage was considered to be complete when the Brain Heart Infusion broth exhibited turbidity. The samples were inspected for turbidity 3, 7, 10, 14 and up to a maximum of 28 days after the start of the experiment Fischer test was used to compare the experimental group.the alpha level for significance was set at p=0.05

17. RESULTS All positive controls showed leakage within 3 days in contrast to the negative controls, which showed no leakage at any time period. All of the experimental samples demonstrated bacterial leakage within 14 days (Table 1). The result of the Fisher’s exact test revealed that there was no significant difference between the two experimental groups at any time period examined (P > 0.05). As a result, the null hypothesis is not rejected at a = 0.05 level.

18. RESULTS OF TWO EXPERIMENTAL GROUPS

19. DISCUSSION COMPARISON WITH PREVIOUS STUDIES In this study, S. mutans, a facultative anaerobic bacterium, was used to test leakage. This model was successfully used in a Resilon leakage study reported by Shipper et al. The major difference from the present study was that post-space was not created in any of their samples and therefore the length of the root fillings tested in their study was at least twice that in the present study.

20. DISCUSSION Shemesh et al. (2006) compared two different experimental models when measuring leakage along root fillings with or without a smear layer; fluid transport and glucose penetration. In one of the experimental groups, Resilon and Epiphany were used as root filling materials. The coronal portion of the filling was removed leaving only 4 mm of it in the canal as per the present study. The results of their experiment showed that glucose penetrated 90% of Resilonfillings within 14 days.

21. DISCUSSION Previous studies results were contradictory. There is only one article to support the timing of post-space preparation affected the root canal seal in canals filled with Resilon/Epiphany (Bodrumlu et al. 2007). Bodrumluet al. (2007) reported that there was significantly more leakage when the post-space was created immediately versus when post-space was created 1 week later.

22. DRAW BACKS OF THE STUDY The present study, which found no significant difference in leakage with regard to the timing of the post-space preparation in root canals filled with Resilon/Epiphany, differs in several ways from that study. The root canals in the present study were prepared to a size-50, .06 taper rotary Sequence file size and filled using the warm vertical compaction, thermoplasticized backfill method versus a final hand file size- 40, 0.02 taper and lateral compaction filler method in the other study

23. DRAW BACKS OF THE STUDY Bacterial leakage was measured over a 28-day period in the current study as opposed to measurement of leakage with a fluid-transport system over one 3-h period in the previous study. There is no mention in the study of Bodrumlu et al. (2007) of the actual number of samples in each group, which leaked, only the mean quantitative leakage for each group is reported. Any one or combination of these factors could explain the difference in results between the two studies

24. LIMITATIONS OF THE STUDY The bacterial penetration model used in this study has its own inherent limitations. It provides qualitative rather than quantitative results. This model only assessed whether there was turbidity created.

25. LIMITATIONS OF THE STUDY The number of bacteria penetrating through the filled canals was not measured; thus the measurements were not quantified by numbers of bacteria penetrating the filled canals

26. LIMITATIONS OF THE STUDY In cases filled with gutta-percha where the post-space preparation has been delayed, it has been reported that the use of Gates-Glidden burs may result in the loss of the seal between the root canal sealer and root canal wall (Goodacre& Spolnik 1995, Schwartz & Robbins 2004). Theoritically if the post-space is created prior to the complete setting of the sealer, the result should be less leakage because the sealer would less likely be disturbed during the removal of the excess Resiloncore with heat and rotary instruments

27. DRAW BACKS OF THE STUDY In the present study, there was no significant difference in the number of specimens that exhibited leakage whether the post-space was created immediately or if the space was created 5 days later. In this ex vivo model the results show that a true monoblock was not achieved in either situation

28. CONCLUSION The results of this ex vivo study demonstrated that there was no significant difference in leakage between the roots with immediate post-space preparation compared to those where post-space preparation was delayed when resilon /epiphany was used as root canal filling material.

29. CONCLUSION Regardless of the timing of the postspace preparation, all experimental specimens leaked within 14 days. These results suggest that in this model there was a failure of the Resilon/Epiphany to create or maintain a true ‘monoblock’ during the post-space preparation procedure

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